Cairo is only available for PHP 5.2+ and PHP 5.3+ The extension also requires the cairo graphics library version 1.4 or higher. The cairo graphics library uses an even and odd numbering scheme to denote stable and unstable library versions. Both unstable and stable versions can be used with the extension, but conditional support for new features is determined by the stable version below the unstable version in use. The latest cairo release can be found at » http://cairographics.org/.
The binary files used for the windows compiles can be found at » http://cairographics.org/download/ along with the project files used to create them.